It is known that the internal combustion engines comprise a lubrication circuit suitable for lubricating the rotating or sliding components of the engine. This lubrication circuit generally comprises an oil pump driven by the engine, which draws lubricating oil from a sump and delivers it under pressure through a main oil gallery that is realized in the cylinder block. The main oil gallery is connected via respective pipes to a plurality of exit holes for lubricating crankshaft bearings (main bearings and big-end bearings), camshaft bearings operating the valves, tappets, and the like.
The lubrication circuit of the turbocharged internal combustion engines further comprises a feeding pipe connecting the main oil gallery to the turbocharger, so as to lubricate the bearings of the rotating shaft connecting the compressor and the turbine of the turbocharger. Due to the very small clearances between the rotating shaft and its bearings, the lubricating oil fed to the turbocharger should be substantially devoid of contaminants, in order to prevent any bearing seizure. For this reason, it is known to locate an additional lubricating oil filter in the feeding pipe connecting the main oil gallery to the turbocharger.
A lubricating oil filter of this kind is realized by integrating a small filter element directly inside a banjo-bolt that is employed for joining the turbocharger feeding pipe to the main oil gallery of the cylinder block. This filter element is currently designed to be effective for the entire life of the internal combustion engine, in order to realize a “for-life filter”. Nonetheless, a clogging of the filter element may occur anyway, due for example to unusually big contaminant particles coming from the lubrication circuit. A clogging of the filter element is very dangerous because it reduces the flow rate of the lubricating oil fed to the turbocharger, thereby increasing the probability of a bearing seizure. The above mentioned “banjo-bolt solution” is unable to handle a clogging of the filter element, so that the turbocharger can be heavily damaged.
In view of the above, it is at least on object to solve this drawback, with a simple, rational and rather inexpensive solution. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.